1. Field of the Invention
This invention relates, generally, to prosthetic devices. More particularly, it relates to a socket having a gelatinous material encased between two thin, flexible plastic covers.
2. Description of the Prior Art
U.S. Pat. No. 5,258,037 to Caspers discloses a prosthetic liner formed of a gelatinous material. It is well-known that a patient using the gelatinous liner must apply large amounts of lotion to the residual limb before using the gelatinous liner because the material is very sticky. Moreover, the gel absorbs body oils and after a few weeks of use it emits strong, disagreeable odors. Still, the gel provides an excellent cushioning effect and thus is widely used by leg amputees.
What is needed, then, is a cushioned prosthetic socket that does not require a user to apply lotions and which does not emit unpleasant odors.
For the past twenty years or so, the leading prosthetic socket has been a socket made of flexible plastic of predetermined thickness. The socket has flexibility due to its plastic construction, but it is not padded and thus does not provide the comfort of the Caspers liner. However, since it is formed of plastic, it is not subject to the limitations of a gelatinous liner.
There is a need, then, for a socket that provides the cleanliness and odor-free service of a conventional plastic flexible socket, but which provides the comfort of a gelatinous liner.
It is also well-known among prosthetists that suction suspension is far superior to any type of mechanical suspension. A drawback to suction suspension arises from the fact that a standard socket, whether flexible or rigid, has a fixed, constant volume. The volume of a residual limb, however, changes during the lifetime of the prosthesis. Prior art attempts to compensate for this volume variation have included the use of silicone liners and inflatable bladders. Silicone liners add considerable weight to the prosthesis, and inflatable bladders require a pump. Moreover, the bladders are easily over-inflated by patients; this can result in damage to the tissue of the residual limb.
Thus, there is a need for an improved volume-adjustment bladder that cannot be over-inflated by the user thereof.
A prosthetic device may be designed for use in above-the-knee, below-the-knee, above-the-elbow, below-the-elbow, and disarticulation (through a joint) applications. The needed improvements in the art should be adaptable to all of such applications, without limitation.
However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in this art how the needed improvements could be provided.